In recent years, consumers have been provided with a variety of devices and systems to enable them to locate specific street addresses on a digital map. These devices and systems are in the form of in-vehicle navigation systems that enable drivers to navigate over streets and roads, portable hand-held devices such as personal digital assistants (“PDAs”), personal navigation devices and cell phones that can do the same, and Internet applications in which users can generate maps showing desired locations. The common aspect in all of these and other types of devices and systems is a map database of geographic features and software to access and manipulate the map database in response to desired user inputs. Essentially, in all of these devices and systems a user can enter a desired location and the returned result will be the position of the desired location. Typically, users will enter an address, the name of a business, such as a restaurant, or a destination landmark, such as the Golden Gate Bridge, and then be returned the location of the requested place. The location may be shown on a map display, or may be used to calculate and display driving directions to the location, or used in other ways.
One problem occurs when a user requests a location having a locality name that is a duplicate of another locality name yet disjoint from the other locality name. A locality is, for example, a city or town within a state, province, county, or other principal geographic unit of interest. Duplicate localities are physically disjoint if they are not contiguous, do not overlap, and are not adjacent. Disjoint localities also do not have any common geographic items, such as street segments, which are portions of streets broken into blocks of street numbers or into other units.
In the United States of America, for example, duplicate yet disjoint localities within a state are common. There are two cities named Washington, New Jersey, and two cities named Burbank, California. There are ten cities named Five Points, Pennsylvania. When duplicate localities have a street name in common, for example when duplicate localities have a street called “Main Street,” a software application needs more information from the user in order to determine which locality the user meant.
An extension of this problem occurs when one of the duplicate localities is known by two or more similar names. For example, Ho-Ho-Kus, New Jersey, may be known by various names, such as Ho-Ho-Kus, Ho Ho Kus or Ho-Ho-Kus (Hohokus), as locality names come from many sources, including administrative, postal, and colloquial sources. Currently, map databases are unable to effectively condense similar names for a locality into a single entry. A map database containing entries for localities, many of which also each have entries for similar names, will have an index that is unwieldy in size for limited-memory navigation devices. Ideally, similar names for a locality would be condensed into a single entry if and only if they represent the same entry. A user who enters Ho-Ho-Kus, Ho Ho Kus or Ho-Ho-Kus (Hohokus) would then find HO HO KUS, as well as duplicate HO HO KUS localities if any exist.
In applications within the United States, a standard method for distinguishing duplicate locality names within the same state or other principal geographic unit of interest is to adorn the duplicates with the name of the county or counties comprising the locality. For example, when a user selects Washington, NJ, MapQuest (www.mapquest.com) adorns the duplicate names with the counties in which they are located, such as Washington, NJ, Warren, US and Washington, NJ, Burlington, US, where Warren and Burlington are counties in New Jersey.
Generally, localities with duplicate names exist in disjoint counties, and therefore county name is distinguishing information that allows an application to determine the unique desired location. One shortcoming of this approach within the United States or Canada is that the location of counties is not widely known outside of a user's local area. Therefore, adorning locality names with county names can force users to choose between unknown locations. This approach is not a particularly useful or robust method of distinguishing similarly named yet disjoint localities for navigation applications. In the United Kingdom, counties play the role of states or provinces in North America, and thus their boundaries are much better known. At the same time, however, the United Kingdom has endemic duplication, overlap and ambiguity of duplicate place names, so that the present approach has serious shortcomings there also.
There is a need to effectively distinguish duplicate yet disjoint localities in the same principal geographic unit of interest, for example a state, in order for map databases to be usable with maximum effectiveness. Instead of adorning duplicate yet disjoint localities with counties, what is needed is a method of adorning duplicate yet disjoint localities with nearby significant cities or towns, such as large cities in close proximity to the duplicate localities that are more likely to be recognizable to the user. Ideally, each duplicate locality would be separately indexed and stored into a map database for use by a software application. There is also a need for adorning a locality with a nearby significant city or town for a user's ease of use, even if not for the purpose of disambiguation of duplicate localities. For a locality having two or more similar names that identify it, there is a need for a way to condense the localities into a single entry in a map database if and only if they represent the same entry, in order to reduce the index size of the database.